1. Anything that is difficult to achieve, and may be put off while simpler alternatives are still available.
2. Matters that take more effort and require more time and are usually most rewarding on a macro level.
3. A person whose association or cooperation with another is of vital importance; supporter.

- slang
Acclaim and Support. “Babe, you’re so magnetic! Very High Hanging Fruit!”.

- antonyms

Low-hanging fruit: quick, easy matters that require little time and usually have a short-term “feel good” effect but yield little in the way of long-term benefit; focussing on granularity.

High Hanging Fruit in foreign policy circles:
A representative responsible for the protection of the interests and nationals of a foreign state, and the promotion of information and friendly relations with a third party. Foreign ministers, excellencies, ambassadors and diplomats.